Audible signal for fire alarms



June 24, 1941. D DAws 2,246,878

AUDIBLE SIGNAL FOR FIRE ALARMS Filed'March 29, 1939 Patented June 24, 1941 AUDIBLE SIGNAL FOR FIRE ALARMS David W. Davis, Washington, D. C.

Application March 29, 1939, Serial No. 264,910

(01. lid-102) 1 is guided and retained within definite confines 7 Claims.

This invention relates to improvements in audible signals for fire alarms and particularly to that type which include a spring motor actuated bell that is released upon variations in temperatures, within definite predetermined ranges.

More specifically the invention includes a spring motor actuated bell in which the striker is driven from a spring motor and is released for actuation upon operation of release mechanism controlled by a thermostatic element.

One of the most important features of the present development is the arrangement of the thermostatic element entirely free of any enclosure so that it is fully subjected to changes in temperature, and which thermostatic element directly engages and actuates a stop mechanism which positively locks the striker in a single predetermined position and which position insures the free movement of the parts in that the dead center position is avoided.

Other objects will more clearly hereinafter appear by reference to the accompanying drawing forming a part of this specification and wherein like numerals of reference designate corresponding parts throughout the several views, in which- Fig. 1 is a top plan view of the mechanism with the spring motor encased in its housing and the bell removed but indicated in dotted line.

Fig. 2 is a side elevation.

Fig. 3 is a transverse section.

Fig. 4 is a fragmentary top plan View showing the thermostatic control.

Fig. 5 is a side elevation of modified form of thermostat.

Fig. 6 is a top plan view of Fig. 5.

Fig. 7 is a top plan view of a second modification and Fig. 8 is a side elevation of same.

Referring to the preferred form of the invention which is illustrated in Figs. 1 to 4 inclusive, the bell is indicated by reference character I and the housing 2 encloses a conventional spring motor mechanism to which is attached the supporting arm 3. The spring motor drives the shaft 4 on which is fixed the eccentric 5 having the stud 6 projecting upwardly therefrom and upon which is mounted the striker arm I. A stud 8 is provided at the opposite side of the spring housing 2 and this stud B has a reduced neck 9 and head In which may be constructed by a separate pin element or a screw which extends into or is fixed in the stud 8. The striker I is formed with a slot II in which th reduced neck 9 of the stud assembly is positioned and whereby the striker during its movement by virtue of rotation of the eccentric 5 to which the free end of the striker is connected by means of the headed stud B. On the upper face of the striker and intermediate the eccentric drive connection 6 and the supporting stud 8 there is provided an extension II! which projects upwardly from the striker arm and which extension or projection is located substantially intermediate the transverse face of the striker.

Supported from the upper face of the spring housing is a support which includes a central body I2 and a plurality of spaced downwardly extending legs M which are fixed to the spring casing in a manner to properly position the support I2 with respect to the housing. The support body I2 is formed with a central opening the axis of which is likewise the axis defining the circumferential outer face of the housing whereby the pin I5, as hereinafter described, may properly function as the locking element for the striker. The pin I5 is fixed centrally within the opening formed in the body I2 of the support by means of the nipple I6. The nipple I5 is threaded at each end as at I! and I8 and the jamb nut I9 is threaded on to the threaded extremity I! and locks this end of the nipple to the body element I2 of the support. The opposite threaded end I8 of the nipple I6 is elongated to provide for the reception of the bell I which latter is formed with a central opening whereby it may be placed in position over this threaded extremity I8 of the nipple I6. A washer 2| of suitable material and preferably containing identification data is placed over the outer surface of the bell I about the threaded extension I8 and the nut 22 is screwed into place. The nipple I6 has its axis opening centrally positioned whereby the pin I5 is aligned in the proper manner.

The pin I5 is formed with a lower reduced extremity 23 and the head 24, the portion immediately below the head being reduced to receive the slotted end of the thermostatic element 25. The thermostatic element 25 is fixed in a horizontal position by the use of the insulating supporting block 25 and screws 21, which latter extend through the thermostat, the block and into the bell to secure these parts together and to hold the thermostat into proper alignment to permit its flexing and consequent shifting of the pin I5.

In operation the thermostat 25 being unconfined and thereby directly exposed to changes in temperature is caused, by virtue of its bi-metallic structure to shift away from the hell I and in so doing the slotted end pulls the pin [5 upwardly and outwardly and away from its engagement with the stop pin l fixed to the upper face of the striker I whereby the striker is released and under power generated by the spring motor in the housing 2 repeatedly driven into sounding contact with the hell I.

In Figures 5 and 6 the same mechanism is utilized with the exception that the le y-metallic spring 30 is of the snap acting type and which type of thermostat will result in a positive quick action of its intermediate portion outwardly as distinguished from a slow pull such as may be present in the thermostat 25. The thermostat 38 is provided with a key slot 3| and its-extremities are secured to the bell by means of screws 32 engaging within the bifurcations as shown.

In the modification shown in Figures '7 and '8 a coil spring is utilized to cause a movement of the pin l5 upwardly and-out-of engagement with the extension of the striker. Toaccomplish this the rotating sleeve -35 is mounted on the upper end of the pin l5 and is formed with a spiral slot 35. The inner extremity of the spring 3! is fixed to this "rotating element 35 and the outer end of the spiral thermostatic spring is fixed to the pin 38. By this arrangement the coiling or uncoi'ling of the .spiral thermostatic spring '31 by virtue of changes in temperature will result in the rotation of the collar 35 and the pin will be moved vertically due to the provision of the small pin-39 which projects from said pin I 5 .and into the spiral groove 36.

What I claim and desire to secure by Letters Patent is:

-1. An audible alarm including a motor, a casing for said motor, a reciprocating striker mounted on said motor casing'an-d driven by said motor, a stop carried by said striker, a bell, a support for said bell fixed to said motor casing, said support including a longitudinal guideway, a lock pin shiftable in said guideway for engagement with the stop on said striker, and a thermostatic element fixed to the outer face of said bell and connected with said lock pin, said thermostatic element being shiftable to move said lock pin out of engagement with the vstopon said striker.

2. The substance of claim 1 characterized in that the stop pin and stop engage only when the drive means is free of dead center position.

3. An audible alarm including a motor, a casing for the motor, a reciprocating striker mounted on said motor casing and driven by said motor, a stop projection carried by said striker, a support fixed to the motor casing, a removable cylindrical member formed with an axial bore carried by said support, said member being formed at a point intermediate its structure with a shoulder portion, a bell formed with a central opening through which said cylindrical member extends, said shoulder engaging said bell about said opening, means for clamping said bell to said cylindrical member, a longitudinally movable stop pin arranged in the bore of said cylindrical member and having a headed portion extending outwardlytherefrom, and a thermostatic element mounted upon the outer face of the bell and connected with the headed portion of said pin, said thermostatic element being adapted to shift said pin upon movement within predetermined temperature .ranges, to cause the latter to be disengaged from said stop on :saidstriker.

'4. The substance of claim 3 characterized in that the thermostatic element is supported by a .heat insulating element on the outer 'face of the bell.

-5. The substance of claim 3 characterized in that the thermostatic element .is removably mounted on an insulating block fixed to the outer face of the bell.

6. The substance of claim 3 characterized in that the thermostatic element is formed with a portion having a snap action which portion is connected to the head of the stop pin.

'7. An audible alarm including a motor, a casing for said motor, a reciprocating striker mounted on said motor casing and driven by said motor, a stop carried by said striker, a bell, a support for the bell fixed to the motor casing, said support having a guideway, a lock pin movable in said guideway for engagement with the stop on said striker, a rotatable sleeve having a spiral slot arranged on said lock pin, said rotatable sleeve being formed with a spiral slot, a pin carried by said stop pin and projecting into said spiral slot, and a coiled thermostat secured at one end to a fixed portion of the assembly and having its other end secured to said rotatable sleeve whereby the expansion and contraction of said thermostat will cause the rotation of said sleeve and the movement of said lock pin out of "engagement with the striker stop.

DAVID 'W. DAVIS. 

